Slings for lifting and carrying heavy pipes or other like heavy objects are known. However, the known slings do not prevent longitudinal twisting and turning of the sling as the heavy pipes or other objects are suspended in mid-air via a closed lifting loop. Moreover, known slings do not provide bi-directional loops which serve to distribute suspension stresses in two directions, longitudinally, along the length or longitudinal axis of the sling when used to complete the closed lifting loop and distribute pulling forces in two directions, longitudinally, along the sling when pulled in any direction. Furthermore, since crane time is very expensive to operate, it is highly desirable to provide a sling system which can accommodate the lifting of a plurality of heavy pipes or other heavy objects simultaneously.
A list of prior patent references which may be of interest is provided below:
Patent No. Inventor Issue Date 1,548,190 Cronqvist 08/04/25 2,357,182 Farmer 08/29/44 2,508,795 Nielsen 05/23/50 3,592,502 Bolliger 07/13/69 3,611,709 Bilbey 10/12/71 3,701,559 Marino et al. 10/31/72 3,840,262 Foster et al. 10/08/74 4,239,271 Beasley et al. 12/16/80 4,431,226 Weilert 02/14/84 4,441,748 St. Germain 04/10/84 4,737,069 Coblentz 04/12/88 4,834,439 van de Kamp 05/30/89 4,856,836 Delphin 08/15/89 4,993,769 Chapalain 02/19/91 5,308,101 Monty 05/03/94 952,210 (GER) 03/11/64 1,516,445 (SU) Volzhsk 10/23/89 2,583,030 (FR) Baroux 12/12/86
In the "sling" art it is known to use a strap of woven or flexible material with loops formed at the terminal ends of the strap; note, for example, the U.S. Pat. No. 3,592,502 patent to Bolliger of Sweden issued in 1971, and the U.S. Pat. No. 4,239,271 patent to Beasley et al issued in 1980.
The Monty patent (U.S. Pat. No. 5,308,108) is directed to an elastic towing strap including an elongated strap having coupled thereto a heavy duty fabric material longer than the non-stretched length of the elastic strap.
The Chapalain patent (U.S. Pat. No. 4,993,769) is directed to a strap having coupled to one end thereof a shackle.
The van de Kamp patent (U.S. Pat. No. 4,834,439) teaches the use of a closed sling of textile webbing material for load lifting which includes four "lifting loops" formed by four slots at greatly spaced locations along of its length, with the closed length webbing material forming four lobes somewhat similar to a four leaf clover. The "lifting loops" are located at the four corners of the cloverleaf lobes into which loops four, converging crane hooks are placed to lift a rectangular, box-like, stacked load carried by the sling. The inner sides of the loops are engaged by oppositely directed, diagonally disposed, tie loops. Although pertinent to the invention, the "loops" and sling of van de Kamp are quite different in structure and use from the sling and sling system of the present invention.
The patent to Coblentz (U.S. Pat. No. 4,737,069) is directed to a method of transporting luggage using a strap having a U-shaped configuration forming first and second end portions. The first and second end portions have coupled thereto a top cross strap and an intermediate cross strap. Furthermore, each end of the first and second end portions forms an end loop.
The Marino et al. patent (U.S. Pat. No. 3,701,559) discloses a sling including four loops having a generally cloverleaf configuration to lift a rectangular, box-like, stacked load carried by the sling.
The French patent document 2,583,030 of Baroux (1980) is directed to a sling for handling a bundle having a continuous, closed member having a supplemental "clamping strap" which is tied across to a loop to enclose the bundle for lifting. There is thus only a single loop along the length of the closed member and the effective diameter is determined by how much of the "clamping strap" is left untied to the loop. This approach likewise is substantially different in structure and use from the present invention.
The nylon sling assembly of Joseph Delphin disclosed in the U.S. Pat. No. 4,856,836 patent uses two straps, each with a variable diameter, end loop, to engage rounded or cylindrical objects useful in the off-loading of cargo to and from an offshore well platform. The loops include above them choker sleeves which slide up and down on the straps to open and close the effective diameters of the loops.
The St. Germain patent (U.S. Pat. No. 4,441,748) is directed to strip thimble for covering a flexible metal cable sling. The strip thimble comprises a fabric strip which includes at least three (3) plies of woven webbing. The strip thimble is coupled to the cable by means of eight (8) spaced friction straps having end portions which are secured between the plies. The straps ends do not extend in a direction parallel to the longitudinal surface of the fabric strip, as does the strap ends of the bi-directional loops of the present invention. Furthermore, the straps are used as a means to maintain the cable within the strip thimble which is substantially different than the present invention.
The Foster et al. patent (U.S. Pat. No. 3,840,262) is directed to a pipe sling having spaced end members with fabric belting material wrapped back and forth between the end members.
The patent to Bilbey (U.S. Pat. No. 3,611,709) issued in 1971 shows the use of the links of the chain as a connecting area for a hook or other type connector.
The patent to Weilert (U.S. Pat. No. 4,431,226) is directed to a large mattress carrying device having a variably adjustable wrap-around band.
The patent to Nielsen (U.S. Pat. No. 2,508,795) is directed to a mattress harness having coupled thereto handle members. The mattress harness is secured around a mattress via a buckle.
The Farmer patent (U.S. Pat. No. 2,357,182) shows a sling which includes a pair of crossed cords or ropes provided with means whereby the ends may be detachably connected together.
The Cronqvist patent (U.S. Pat. No. 1,548,190) is directed to a spar-tree strap having a plurality of links which is essentially made of a steel cable. Each distal end of a link has secured thereto an eye for receiving therethrough adjacent links to form a strap around a tree in a closed loop manner.
The Russian Patent (1,516,445) by Volzhsk is directed to a sling having a rope with a clasping device. Around the rope are loops formed by the attachment of short lengths of additional rope to the main rope by clamps.
The British Patent No. 952,210 published Mar. 11, 1964, is directed to lifting belts for use in righting de-railed vehicles. The lifting belt comprises a wire rope bent into a U-shape forming two substantially parallel portions which are connected together at intervals along their lengths by U-shaped wire-rope cross members.
As can be readily seen, there is a continuing need to provide a sling with at least one bi-directional loop or a plurality of bi-directional loops which serve to distribute suspension stresses in two directions, longitudinally, along the lifting straps when used to complete the closed lifting loop and distribute pulling forces in two directions, longitudinally, along the sling when pulled in any direction. Furthermore, since crane time is very expensive to operate, it is highly desirable to provide a sling system which can accommodate the lifting of a plurality of heavy pipes or other heavy objects simultaneously. As will be seen more fully below, the present invention is substantially different in structure, methodology and approach from that of the prior art slings.